When a user displays information on a display such as a monitor of a television set or a personal computer and enjoys the information, typically, one kind of information is displayed on the display. When the user displays and obtains different kinds of information, the user switches a channel or switches a window of an application software. In this case, when the user alone uses the television set or the personal computer or when all people want to watch the same information, no problem occurs. However, even if there are requests in which people would like to simultaneously watch different kinds of information, the requests cannot be met. To display a plurality of screens on one display surface, for example, the screens can be displayed by two-screen display for dividing the display surface into two or multi-windows for opening application software in a plurality of windows. However, there is not only a problem in that the screen size of each of the screens is reduced but also a problem in that, if a screen other than a screen that a user desires to watch is displayed next to the desired screen, the screen is annoying.
On the other hand, recently, a service for setting a large display in a public space and providing information has been widely used. However, if only one kind of information can be provided to a large number of people, efficiency of information transfer is low and diversified requests of users cannot be satisfied.
An image multiplex display system is proposed in which a plurality of kinds of information are multiplexed and displayed on one display surface and a plurality of users can respectively select and observe desired kinds of information. This system can meet diversified requests of the users.
As an example of the image multiplex display system, JP62-65580A (hereinafter referred to as Patent Literature 1) describes a system that displays a plurality of kinds of information on one display surface in a time division manner. A user observes a desired kind of information wearing shutter glasses that opens and closes in synchronization with display of the desired image information. Further, Patent Literature 1 describes a system that displays first and second polarized images having different polarized light components on the same screen in a time division manner. In this system, a user wearing polarization glasses that transmit only first polarized light can observe the first polarized image and a user wearing polarization glasses that transmit only second polarized light can observe the second polarized image.
JP62-91926 (hereinafter referred to as Patent Literature 2) describes a double broadcast system including a projection type display apparatus. When the projection type display apparatus is used, it is possible to combine two polarized images on a screen using two projecting apparatuses besides switching a polarization direction using one display apparatus in a time division manner. In this case, as in the case explained above, a user observes information wearing polarization glasses.
As a technique related to polarization glasses, which is not an image multiplex display system, JP05-323267 (hereinafter referred to as Patent Literature 3) discloses polarization glasses including polarization direction variable means. In the polarization glasses of Patent Literatures 1 and 2, a user has to wear different glasses according to a selected polarization direction. However, when this technique is used, the user can select a polarized image with one pair of glasses.